Question

Give the order of reactivity of dihydrogen with the halogens.

Answer 1

(i) The reaction between fluorine and hydrogen is an explosive reaction even when it is cold and dark.  

(ii) The reaction between chlorine and hydrogen is an explosive reaction but only when it occurs in the presence of heat and light.  

(iii) The reaction between bromine and hydrogen is a little less explosive and this explosion occurs only when exposed to flames.

(iv) There is only partial reaction happening between Iodine and hydrogen achieving the state of chemical equilibrium .

Hence, the order of reactivity would be HF > HCl > HBr > HI.